The present invention concerns the field of image processing, particularly of three-dimensional radiological images.
As is known, radiological apparatuses comprise a means of emission of an X-ray beam such as an X-ray tube and a means of reception of the beam, such as a solid state detector or even a scintillator and a video camera, of CCD type, for example.
The means of emission and the means of reception of X-rays are generally supported by a mobile system with one or more axes, making it possible to take pictures at different angles of incidence. The means of reception of the X-ray beam is connected to image processing means making possible the generation of so-called 3DXA three-dimensional images from a series of two-dimensional images picked up by the means of reception, these two-dimensional images being representative of the group of structures crossed by the X-rays. In a 3DXA three-dimensional image, the voxels are isotropic and have a dimension in the order of 300 μm. In angiography applications, the 3DXA images make it possible to see the blood vessels which are injected with contrast medium, but the other tissues can hardly be distinguished.
The nuclear magnetic resonance apparatuses comprise means of sectional imaging, an image being representative of the proportion of water present in the structures observed. From a series of such so-called MR images taken along different cutting planes displaced in translation and/or in rotation, it is known how to reconstruct a so-called 3DMR three-dimensional image. In a 3DMR three-dimensional image, the voxels are anisotropic, that is, capable of having different dimensions along the axes of a three-dimensional mark. The resolution is in the order of one millimeter. In angiography, applications the 3DMR images make it possible to see the blood vessels and other tissues.
It is important to obtain a good match between a 3DXA image and a 3DMR image in order to refine the knowledge of the structures observed, notably, of the blood vessels in their environment.
Such a match can be obtained by external markers, use of which is constraining and creates risks of errors.
The present invention is an improved method of registration.
The present invention also concerns a method of registration of millimetric or submillimetric precision with short calculation time.
The automatic registration method in an embodiment of the invention is intended for three-dimensional images making possible a good visualization of the blood vessels.